Threaded Insert Sealing in Casting Molds to Block Melt Infiltration

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Solution Overview

Problem

Current methods for casting threaded inserts into metal or plastic components face challenges in preventing molten metal or plastic from infiltrating the insert, leading to weakened threads and mechanical stress due to material shrinkage during cooling, especially in pressure-assisted casting processes.

Innovation Solution

A metal casting or plastic injection molding process that uses a mold with a flexible sealing element and a holding core to position and secure the insert, preventing molten material infiltration and accommodating material shrinkage through temperature-resistant and heat-dependent plastic materials with predetermined breaking points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If threaded inserts are cast into molten metal or plastic, then the insert can be integrated into the component, but the liquid material infiltrates the insert and impairs its function

Engineering Contradiction:

Improveinsert functionVSAvoidmaterial infiltration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A sealing element is introduced as an intermediary component between the insert and the mold cavity wall. This sealing element prevents direct contact between the molten material and the insert, thereby blocking infiltration while allowing the insert to remain integrated in the component.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing element is designed as a flexible component that can deform to accommodate the insert and seal against the mold cavity wall. This flexible structure effectively blocks the infiltration path of molten material while maintaining system integrity.

Inventive Principle:

Principle #30Flexible shells and thin films

2Manufacturing precision

If the insert is held rigidly in the mold, then positioning is precise, but material shrinkage during cooling creates mechanical stress

Engineering Contradiction:

Improveinsert positioningVSAvoidcomponent strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The holding core is designed with movable capability rather than being completely rigid. This allows the holding core to move slightly during cooling to accommodate material shrinkage, reducing mechanical stress while maintaining positioning precision through controlled movement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The holding core's mechanical properties are designed to change with temperature. At casting temperature, it provides rigid support for precise positioning; during cooling, it becomes more compliant to accommodate shrinkage and reduce stress.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a sealing element is added to prevent infiltration, then insert function is protected, but device complexity increases

Engineering Contradiction:

Improveinsert functionVSAvoidmold structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The holding core is designed to perform multiple functions: it positions the insert, provides support during casting, and incorporates sealing functionality. By integrating these functions into a single component, the overall device complexity is minimized while still protecting insert function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sealing function is merged with the holding core structure rather than being a separate component. This integration reduces the number of parts and simplifies the mold structure while effectively preventing material infiltration.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively prevents molten material infiltration and reduces mechanical stress in the cast component by allowing the insert to move freely during cooling, ensuring the integrity and strength of the threaded inserts.

Implementation Method 1

the inner wall of the inner cavity (6) is coated with plastic in a sealing manner, in that the plastic closes gaps and cavities in a sealing manner

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

The plastic of the holding core (40) has an approximately heat-independent strength or a heat-dependent strength which decreases with increasing thermal stress

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

with the plastic having at least one predetermined breaking point (18), which ensures failure of the holding core transversely to a longitudinal direction of the holding core

Methodology Applied

Scientific EffectFracture mechanics: Fracture Mechanics

Data Source

PatentEP3126116B1Insert for a casting mold and a casting method

Publication Date: 2022.06.01 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

Figure 1~3
Figure 4a~4b
Figure 5a~5c

AI summary

The present invention describes a metal casting method and a plastics injection molding method in which a material melt is cast around an insert in such a way that the material melt does not penetrate into the interior of the insert. The use of a wire thread insert as the insert has the advantage that threaded holes can be produced for example in a cast aluminum part already during the casting process. For this purpose, the present invention discloses the corresponding casting mold, the insert and the casting method.